scholarly journals A room, a bar and a classroom: how the coronavirus is spread through the air depends on heavily mask filtration efficiency

2020 ◽  
Author(s):  
Devabhaktuni Srikrishna
Keyword(s):  
Face Mask ◽  
Infection Risk ◽  
Filtration Efficiency ◽  
Transmission Risk ◽  
Infected Person ◽  
Short Supply ◽  
Infectious Individual ◽  
Healthcare Settings ◽  
Poor Ventilation ◽  
N95 Respirators

AbstractBackgroundRecently the US CDC acknowledged by that the COVID-19 crisis is facilitated at least in part by aerosolized virus exhaled by symptomatic, asymptomatic, or pre-symptomatic infected individuals. Disposable N95 masks remain in short supply due to their use in healthcare settings during the Coronavirus pandemic, whereas NIOSH-approved elastomeric N95 (eN95) masks remain immediately available for use by essential workers and the general public. New reusable N95 mask options with symmetric filtration efficiency can be anticipated to be NIOSH approved in the coming months, today’s eN95 masks have asymmetric filtration efficiency upon inhalation (95%) and exhalation (well under 95%) but are available now during the Fall and Winter when Coronavirus cases are expected to peak.MethodsBased on the Wells-Riley model of infection risk, we examine how the rate of transmission of the virus from one infected person in a closed, congested room with poor ventilation to several other susceptible individuals is impacted by the filtration efficiency of the masks they are wearing. Three scenarios are modeled – a room (6 people, 12’ × 20’ × 10’), a bar (18 people, 20’ × 40’ × 10’), and a classroom (26 people, 20’ × 30’ × 10’) with one infectious individual and remaining susceptibles. By dynamically estimating the accumulation of virus in aerosols exhaled by the infected person in these congested spaces for four hours using a “box model,” we compare the transmission risk (probability) when susceptible people based on a realistic hypothesis of face mask protection during inhaling and exhaling e.g. using cloth masks or N95 respirators.ResultsAcross all three scenarios, cloth masks modeled with 30% symmetric filtration efficiency alone were insufficient to stop the spread (18% to 40% infection risk), whereas eN95 masks (modeled as 95% filtration efficiency on inhalation, 30% on exhalation) reduced the infection risk to 1.5% to 3.6%. Symmetric filtration of 80% reduces the risk to 1.7% to 4.1% and symmetric filtration of 95% would further reduce the risk to 0.11% to 0.26%.ConclusionThis modeling of mask filtration efficiency suggests that the pandemic could be readily controlled within several weeks if (in conjunction with sensible hygiene) a sufficiently large majority of people wear asymmetric but higher-filtration masks (e.g. eN95) that also block aerosols whenever exposed to anyone else outside their household in order to completely stop inter-household spread.

scholarly journals Why simple face masks are unexpectedly efficient in reducing viral aerosol transmissions

2020 ◽  
Author(s):  
Steffen Freitag ◽  
Steven G. Howell ◽  
Kevin T. C. Jim
Keyword(s):  
Viral Load ◽  
Face Mask ◽  
Respiratory Viruses ◽  
Filtration Efficiency ◽  
Size Distributions ◽  
The Past ◽  
Apparent Inconsistency ◽  
Viral Aerosol ◽  
N95 Respirators ◽  
Aerosol Volume

SummaryDuring the current pandemic and in the past, shortages of high quality respirators have forced people to protect themselves with homemade face masks that filter poorly in comparison to N95 respirators 1–4 and are often designed in ways that makes them susceptible to leaks 5,6. Nevertheless, there is compelling epidemiological 7,8 and laboratory evidence 9–12 that face masks can be effective in impeding the spread of respiratory viruses such as influenza and SARS-CoV-2. Here we show that this apparent inconsistency can be resolved with a simple face mask model that combines our filtration efficiency measurements of various mask materials with existing data on exhaled aerosol characteristics. By reanalyzing these data we are able to reconcile the vastly different aerosol size distributions reported 13–19 and derive representative volume distributions for speech and breath aerosol. Multiplying filtration efficiency by those aerosol volumes, which are proportional to emitted viral load, shows that electrostatically charged materials perform the best but that even most uncharged fabrics remove > 85 % of breath and > 99 % of speech aerosol volume for exhaled particles < 10 µm in diameter. A leak model we develop shows the best uncharged fabric masks are made of highly air-permeable and often thin materials reducing viral load by up to 45 % and 50 % for breath and speech, respectively. Less permeable materials provide reduced protection because unfiltered air is forced through the leak. This can even render some charged materials inferior to uncharged household materials. Our model also shows that thin fabric masks provide protection for the wearer from aerosols expelled by another person reducing inhaled viral load by up to 20 % and 50 % and if leaks are avoided up to 35 % and 90 % for breath and speech, respectively.

Study of face mask filtration efficiency to prevent fine dust to secure people’s right to health

2020 ◽  
Vol 19 (2) ◽  
pp. 186-193
Author(s):  
Woo-Taeg Kwon ◽  
◽  
Min-Jae Jung ◽  
Bum-Soo Kim ◽  
Woo-Sik Lee ◽  
...  
Keyword(s):  
Face Mask ◽  
Right To Health ◽  
Filtration Efficiency ◽  
Fine Dust

Cost-Effective Face Mask Filter Based on Hybrid Composite Nanofibrous Layers with High Filtration Efficiency

Langmuir ◽  
2021 ◽  
Author(s):  
Walaa A. Abbas ◽  
Basamat S. Shaheen ◽  
Loujain G. Ghanem ◽  
Ibrahim M. Badawy ◽  
Mohamed M. Abodouh ◽  
...  
Keyword(s):  
Hybrid Composite ◽  
Cost Effective ◽  
Face Mask ◽  
Filtration Efficiency

scholarly journals The protective performance of reusable cloth face masks, disposable procedure masks, KN95 masks and N95 respirators: Filtration and total inward leakage

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258191
Author(s):  
Scott Duncan ◽  
Paul Bodurtha ◽  
Syed Naqvi
Keyword(s):  
Geometric Mean ◽  
Particle Diameter ◽  
Standing Position ◽  
Filtration Efficiency ◽  
Protection Factor ◽  
Respiratory Illnesses ◽  
Particle Penetration ◽  
Preventive Health Measure ◽  
Materials Used ◽  
N95 Respirators

Face coverings are a key component of preventive health measure strategies to mitigate the spread of respiratory illnesses. In this study five groups of masks were investigated that are of particular relevance to the SARS-CoV-2 pandemic: re-usable, fabric two-layer and multi-layer masks, disposable procedure/surgical masks, KN95 and N95 filtering facepiece respirators. Experimental work focussed on the particle penetration through mask materials as a function of particle diameter, and the total inward leakage protection performance of the mask system. Geometric mean fabric protection factors varied from 1.78 to 144.5 for the fabric two-layer and KN95 materials, corresponding to overall filtration efficiencies of 43.8% and 99.3% using a flow rate of 17 L/min, equivalent to a breathing expiration rate for a person in a sedentary or standing position conversing with another individual. Geometric mean total inward leakage protection factors for the 2-layer, multi-layer and procedure masks were <2.3, while 6.2 was achieved for the KN95 masks. The highest values were measured for the N95 group at 165.7. Mask performance is dominated by face seal leakage. Despite the additional filtering layers added to cloth masks, and the higher filtration efficiency of the materials used in disposable procedure and KN95 masks, the total inward leakage protection factor was only marginally improved. N95 FFRs were the only mask group investigated that provided not only high filtration efficiency but high total inward leakage protection, and remain the best option to protect individuals from exposure to aerosol in high risk settings. The Mask Quality Factor and total inward leakage performance are very useful to determine the best options for masking. However, it is highly recommended that testing is undertaken on prospective products, or guidance is sought from impartial authorities, to confirm they meet any implied standards.

scholarly journals Perception and awareness of COVID-19 among health science students and staff of Kuwait University: An online cross-sectional study

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 566
Author(s):  
Walid Alali ◽  
Wadha AlFouzan ◽  
Dhuha Alajmi ◽  
Haya Al-Tawalah ◽  
Khalid Kheirallah ◽  
...  
Keyword(s):  
Social Stigma ◽  
Face Mask ◽  
Health Science ◽  
Vaccine Uptake ◽  
Transmission Risk ◽  
Science Students ◽  
Online Questionnaire ◽  
Cross Sectional ◽  
Kuwait University ◽  
Health Science Students

Background: Coronavirus disease 2019 (COVID-19) pandemic is unprecedented. Health science students are the future frontliners to fight pandemics. Awareness and perception toward COVID-19 among health science students and staff at Kuwait University was assessed. Methods: Between June and July 2020, an online questionnaire was distributed to all students and staff at HCS.  The questionnaire was divided into six sections: socio-demography, risk and awareness, preparedness and prevention, source of information, policies, and social stigma.  Results: A total of 592 students and 162 staff completed the questionnaire. The prevalence of self-reported chronic condition among students and staff was 14.0% and 19.1%, respectively. Moreover, self-reported COVID-19 prevalence among students and staff was 2.7% and 1.2%, respectively. Interestingly, 54% of students and 38.3% of staff reported that they knew someone within their immediate social environment who have been/are infected with SARS-CoV-2. Among students, 92.4% wore face mask in indoor places (outside of their home) ‘often/all the time’ compared to wearing it outdoors (69.3%); whereas, for staff, it was more common to wear it outdoor than in indoor places (75.9% vs. 81.5%). Willingness to take COVID-19 vaccine was indicated by 50% of students ‘strongly agreed’ and an additional 25.8% agreed to taking it. Interest vaccine uptake was lower among staff (28.4% and 34.6% strongly agreed or agreed, respectively). Participants strongly agreed or agreed (72.5% and 19.6% of students as well as 68.5% and 22.2% of staff) that wearing face mask in public should be obligatory. More than 18% of students and staff indicated that they would avoid contact with COVID-19 infected people. Conclusions: Responses of students and staff were mostly similar and showed that they follow precautionary measures to control spread of COVID-19, understand the viral transmission risk, and willing to raise awareness to reduce social stigma.

scholarly journals 3D Printed frames to enable reuse and improve the fit of N95 and KN95 respirators

2020 ◽  
Author(s):  
Malia McAvoy ◽  
Ai-Tram N. Bui ◽  
Christopher Hansen ◽  
Deborah Plana ◽  
Jordan T. Said ◽  
...  
Keyword(s):  
3D Printing ◽  
Design Process ◽  
Clinical Settings ◽  
Short Supply ◽  
Iterative Design ◽  
Healthcare Settings ◽  
Fit Testing ◽  
3D Printed ◽  
Single Use ◽  
Repeated Use

Background: In response to supply shortages during the COVID-19 pandemic, N95 filtering facepiece respirators (FFRs or "masks"), which are typically single-use devices in healthcare settings, are routinely being used for prolonged periods and in some cases decontaminated under "reuse" and "extended use" policies. However, the reusability of N95 masks is often limited by degradation or breakage of elastic head bands and issues with mask fit after repeated use. The purpose of this study was to develop a frame for N95 masks, using readily available materials and 3D printing, which could replace defective or broken bands and improve fit. Results: An iterative design process yielded a mask frame consisting of two 3D-printed side pieces, malleable wire links that users press against their face, and cut lengths of elastic material that go around the head to hold the frame and mask in place. Volunteers (n= 41; average BMI= 25.5), of whom 31 were women, underwent qualitative fit with and without mask frames and one or more of four different brands of FFRs conforming to US N95 or Chinese KN95 standards. Masks passed qualitative fit testing in the absence of a frame at rates varying from 48-92% (depending on mask model and tester). For individuals for whom a mask passed testing, 75-100% (average = 86%) also passed testing with a frame holding the mask in place. Among users for whom a mask failed in initial fit testing, 41% passed using a frame. Success varied with mask model and across individuals. Conclusions: The use of mask frames can prolong the lifespan of N95 and KN95 masks by serving as a substitute for broken or defective bands without adversely affecting fit. Frames also have the potential to improve fit for some individuals who cannot fit existing masks. Frames therefore represent a simple and inexpensive way of extending the life and utility of PPE in short supply. For clinicians and institutions interested in mask frames, designs and specifications are provided without restriction for use or modification. To ensure adequate performance in clinical settings, qualitative fit testing with user-specific masks and frames is required.

scholarly journals Filtration Efficiency of Hospital Face Mask Alternatives Available for Use During the COVID-19 Pandemic

2020 ◽  
Vol 180 (12) ◽  
pp. 1607 ◽  
Author(s):  
Emily E. Sickbert-Bennett ◽  
James M. Samet ◽  
Phillip W. Clapp ◽  
Hao Chen ◽  
Jon Berntsen ◽  
...  
Keyword(s):  
Face Mask ◽  
Filtration Efficiency

Respiratory Protection by Respirators: The Predictive Value of User Seal Check for the Fit Determination in Healthcare Settings

2011 ◽  
Vol 32 (4) ◽  
pp. 402-403 ◽  
Author(s):  
Simon Ching Lam ◽  
Joseph Kok Long Lee ◽  
Linda Yin King Lee ◽  
Ka Fai Wong ◽  
Cathy Nga Yan Lee
Keyword(s):  
Electronic Device ◽  
World Health ◽  
Respiratory Pathogens ◽  
Respiratory Protection ◽  
Healthcare Settings ◽  
The World ◽  
Fit Testing ◽  
Control And Prevention ◽  
Health Organization ◽  
N95 Respirators

The N95 respirator is one type that is recommended by the World Health Organization and the Centers for Disease Control and Prevention (CDC) to prevent inhalation of droplets that may act to transmit respiratory pathogens. However, the reliability of this respirator to prevent transmission is dependent on how well it is fitted to the wearer. For ill-fitting respirators, the average penetration by ambient aerosol was found to be 33%, compared with 4% for well-fitting respirators. Such penetration or leakage may be caused by the gap between the respirator and the wearer's face. Therefore, formal fit testing should be carried out prior to the use of N95 respirators. Quantitative fit testing measures “the adequacy of respirator fit by numerically measuring the amount of leakage into the respirator” using an electronic device.

scholarly journals Scalable In-hospital Decontamination of N95 Filtering Facepiece Respirator with a Peracetic Acid Room Disinfection System

2020 ◽  
Author(s):  
Amrita R. John ◽  
Shine Raju ◽  
Jennifer L. Cadnum ◽  
Kipum Lee ◽  
Phillip McClellan ◽  
...  
Keyword(s):  
Peracetic Acid ◽  
Structural Integrity ◽  
Filtration Efficiency ◽  
Material Structure ◽  
Cycle Duration ◽  
Bacteriophage Ms2 ◽  
Large Numbers ◽  
Care Workers ◽  
High Level ◽  
N95 Respirators

AbstractBackgroundCritical shortages of personal protective equipment (PPE) especially N95 respirators, during the SARS-CoV-2 pandemic continues to be a source of great concern among health care workers (HCWs). Novel methods of N95 filtering facepiece respirator (FFR) decontamination that can be scaled-up for in-hospital use can help address this concern and keep HCWs safe.MethodsA multidisciplinary pragmatic study was conducted to evaluate the use of an ultrasonic room high-level disinfection system (HLDS) that generates aerosolized peracetic acid (PAA) and hydrogen peroxide for decontamination of large numbers of N95 respirators. A cycle duration that consistently achieved disinfection of N95 respirators (defined as ≤ 6 log10 reductions in bacteriophage MS2 and Geobacillus stearothermophilus spores inoculated onto respirators) was identified. The treated masks were then assessed for changes to their hydrophobicity, material structure, strap elasticity, and filtration efficiency (FE). Assessment of PAA off-gassing from a treated mask was also performed.ResultsThe PAA room HLDS was effective for disinfection of N95 respirators in a 2447 cubic feet room with deploy and dwell times of 16 and 32 minutes respectively, and a total cycle time of 1 hour and 16 minutes. After 5 treatment cycles, no adverse effects were detected on filtration efficiency, structural integrity, or strap elasticity. There was no detectable off-gassing of PAA from the treated masks.ConclusionThe PAA room disinfection system provides a rapidly scalable solution for in-hospital decontamination of large numbers of N95 respirators to meet the needs of HCWs during the SARS-CoV-2 pandemic.

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